Regulation of aging by unc-13 and sbt-1 in Caenorhabditis elegans is temperature-dependent.

OBJECTIVE: To investigate the role of environmental factor-temperature in the regulation of aging process by unc-13 and sbt-1 in Caenorhabditis elegans.
METHODS: The lifespan, the speed of pharynx pumping, and the intestinal autofluorescence of unc-13 and sbt-1 mutants were examined at different temperature conditions. In addition, to exclude the possible influences from other factors in unc-13 and sbt-1 mutants, the dauer formation, the thermotaxis, the brood size and the population percentage of the mutants expressing hsp16.2-gfp were further investigated.
RESULTS: Mutations of unc-13 and sbt-1 significantly increased the mean and the maximum lifespans of nematodes cultured at 20 degrees C and 25 degrees C, while no noticeable increase was found at 15 degrees C in either the mean or the maximum lifespan. Investigations on the speed of pharynx pumping and the intestinal autofluorescence suggested that at 20 degrees C and 25 degrees C, mutations of unc-13 and sbt-1 could slow the aging process and delay the accumulation of aging-related cellular damage. Meanwhile, mutations of unc-13 or sbt-1 did not affect the dauer formation or the thermotaxis to different temperatures in nematodes. In contrast, at 20 degrees C and 25 degrees C conditions, mutations of unc-13 and sbt-1 significantly decreased the brood size and the percentage of nematodes expressing hsp16.2-gfp, while no such differences were detected at 15 degrees C. Moreover, the thermotolerance of unc-13 and sbt-1 mutants could be greatly strengthened after the 16-h heat shock at 35 degrees C.
CONCLUSION: The regulation of aging by unc-13 and sbt-1 is temperature-dependent. And the alterations in reproduction capability and stress response may be associated with the formation of this temperature-dependent property.